(a-b)的四次幂展开式是?
问题描述：
(a-b)的四次幂展开式是?
答
=（a^2+b^2+2ab）^2 =a^4+(b^2+2ab)^2+2a^2(b^2+2ab) =a^4+b^4+4a^2b^2+4ab^3+2a^2b^2+4a^3b
(a-b)的四次幂展开式是?
=（a^2+b^2+2ab）^2 =a^4+(b^2+2ab)^2+2a^2(b^2+2ab) =a^4+b^4+4a^2b^2+4ab^3+2a^2b^2+4a^3b